Abstract: Aspects of the subject technology provide improved techniques for determining a state of an audio device, including reduced power techniques for determining if an earbud is currently being worn in a user's ear or not. In aspects, a potential state change in an audio device may be detected, and in response measurement of the state of the device may be initiated, such as by emitting an audio signal and then determining the state of the audio device based on a sensed version of the emitted audio signal.